/ˌjuː ˌdiː ˈpiː/
noun — "the lightweight protocol that sends data without waiting for confirmation."
UDP, short for User Datagram Protocol, is a transport-layer protocol in the IP suite that allows applications to send messages, called datagrams, without establishing a connection or guaranteeing delivery. Unlike TCP (TCP), UDP is connectionless and does not perform error correction, flow control, or retransmission, making it faster and more efficient for scenarios where speed and low latency are critical.
Technically, each UDP datagram consists of a header and payload. The header contains source and destination ports, length, and a checksum for optional integrity verification. Because it lacks session management, UDP is ideal for broadcasting or multicasting data where occasional packet loss is acceptable. It is widely used in applications such as live video streaming, VoIP, online gaming, and DNS queries.
Key characteristics of UDP include:
- Connectionless: does not establish a session before transmitting data.
- Low overhead: minimal header information reduces latency.
- Unreliable delivery: packets may be lost or arrive out of order.
- Supports broadcast and multicast: enables efficient transmission to multiple devices.
- Fast and lightweight: suitable for real-time applications.
In practical workflows, UDP is used when applications prioritize speed over reliability. For example, video conferencing software transmits audio and video streams via UDP to minimize latency, accepting occasional lost packets. Network engineers configure firewalls and routers to handle UDP traffic efficiently while ensuring security and proper port management.
Conceptually, UDP is like sending postcards instead of certified letters: each message goes out immediately without acknowledgment, trusting the system to deliver most of them quickly.
Intuition anchor: UDP trades guaranteed delivery for speed, powering applications where responsiveness is more important than perfection.